This pale yellow, shrub-like lichen grows exclusively on the twigs of pencil pine (Athrotaxis cupressoides), a rare Tasmanian conifer.

Described by Australian scientist Gintaras Kantvilas in 1990, it can be distinguished from related lichens by its unique chemistry, including traces of usnic acid, and its cottony texture that forms patches up to 1 centimetre across.

It is found exclusively in association with Athrotaxis cupressoides, an endemic Tasmanian conifer, in a restricted alpine within the Walls of Jerusalem National Park.

[2] Roccellinastrum flavescens is known only from Tasmania, where it grows on the living and dead twigs of Athrotaxis cupressoides, a fire-sensitive conifer endemic to the region.

However, unlike these lichens, which tend to develop fully on older leafless twigs, R. flavescens prefers the youngest shoots that still retain living leaves, indicating a particular ecological niche.

The distinct yellow hue and cottony structure of R. flavescens make it readily identifiable within the Tasmanian lichen flora, and it is unlikely to be confused with other species in the region.